medication calculation for Mefoxin

  1. I would appreciate any help with this med calc problem. It's one of few I'm stumbling over for next semester.

    Dr.'s order: Mefoxin (cefoxitin sodium) 100mg/kg/day IV q 4 hours

    Pharmacy sends: Mefoxin (cefoxitin sodium) 1 gram to be diluted with 10ml NS.

    Child weighs: 15lbs = 6.82kgs

    A. How many milligrams of Mefoxin per day will this 15lb child receive?
    6.82kgs x 100mg/kg/day= 682mg/day

    B. How many milligrams per dose Mefoxin will the nurse administer?

    C. How many mL of Mefoxin will the nurse administer with each dose?

    B & C have me stumped
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    Joined: Nov '08; Posts: 3


  3. by   anonymousstudent
    I think you already did the hard part!

    To figure out B, you need to divide the total amount of the drug by the number of times it's to be given per day.

    C is harder...if 1 g is diluted with 10 mL of NS, the same percentage relationship applies to your answer to B and the amount of NS.
  4. by   RNw11
    thank you so much. brain fart on B but C definitely needed some explaining.
    Thank You again!
  5. by   njmomstudent
    Well, for B you would divide 682/6 since its every 4 hours and I get 113.7mg per dose.

    For C, you have 1000mg/10ml. I still use my general algebra equation for everything.

    1000mg/113.7mg=10mL/xmL. Then you cross multiply and its easier to see when you have it written old school fraction style with the line directly under the top number. But basically ends up 1000x=1137. x=1137/1000. SO x=1.137 rounded to whatever your instructor wants, I would guess 1.1ml.
  6. by   RNw11
    Excellent! the answers were posted & that is it!
    Thank you a bunch!